High air capacity self-priming pump



Aug. l1, 1942. H. E. LA BoUR 2,292,530 A I HIGH AIR CAPACITY SLF-RIMING PUMP Filed NOV. l0, 1939 recirculation l actual interference with ,the

Parenteel Aug. 11, 1942 UNITED STATES' lPATENT OFFICE 2,292,530

HIGH Am CAPACITY SELF-ranma PUMP Han-y E. La Bour, Elkhart, ma. y i Application November 1o, 1939, serial No. 303,718 6 claims. (c1. 10s-113) 'I'he present invention relates to self-primingcentrifugal pumps and .the principal object of the invention is to provide means for rendering a self-priming centrifugal pump of the air-entrainment liquid-recirculating type capable of rapid removal of air from the suction side of the pump throughout the entirerange of suctions of which it is capable.

While I have shown herein a specic embodiment of the invention, this is by waycf illustration rather than limitation. The 'principle herein disclosed may be embodied in a wide variety of centrifugal pumps, including the concentric type, the volute type, the turbine type, and others. The shaft of the pump may be horizontal or ver tical without departure from the invention.

From observation and experiments, I have de-` termmed that of the uid recirculated for producing a maximum rate of gas removal, other things being If too little liquid relative to the size of the pump is recirculated the effectiveness of` airrremoval suiers for lack of suicient vol- `ume of entraining and carrying medium. If the stream is so small relative to the physical dimensions of thepump that the ow of fluid fails to ll the discharge kinetic energy is developed into pressure, the op..

eration is unsatisfactory. On the other hand, if

the recirculated stream is more than enough to ll the discharge throat, the operation involves not' only idle movement of liquid but results in formation and discharge of a proper mixture of gas and liquid. In other Words, there must be sutcient liquid to providea full discharge of the mixture, and, at the same time,v theremust be the proper gas to liquid ratio. On the other hand, there must not be so much liquid in` the circulation as to produce overlling of the impeller and discharge, nor to produce a gas to liquid ratio which is too low. The present invention aims to contol the size of the recirculation stream whereby to obtain rapid air removal.

`Various forms of self-priming centrifugal pumps are now on the market. One of the best known forms is that involving the use of the socalled'hydraulic balance to turn of water to the pump casing under the higher vacuums. 'I'his pump is throat where V prevent excessive reshown in my Patent N o. 1,578,236, and a specific form of throating commercially employed is shown in my Patent No. 2,163,951. According tothe principle of that ery of the impeller.

This system and method of operation has been highly successful,

and from then functions to prevent the reentry of further liquid. 'I'he difficulty in getting water back into the impeller under low vacuum conditions materially retards the priming speed. i

Another scheme which is in common use provides for the return and recirculation of liquid from the separator back to the suction side of .the This general scheme may be divided into several sub-classifications, the shortcomings of which will be pointed out below. The simplest arrangementA is a connection be. tween the separator and the pump suction, which connection is Wide open at all times, but is restricted in size so as to limit the amount of liquid which can be returned. Since the direction of ow is always of liquid returned from the discharge back to the suction is in direct proportion to the diierence in pressures, it

been Icon'ipleted the'rate of ow back to the suc- -tion is greatest, and inversely, when the cycle ably the poorest methody of self-priming now in e. Another scheme provides for a controlling l is obvious that after prime has 2 seasso valve -in the by-pass. The actuating element of intake of the impeller chamber. To determine this valve is located in the stream of discharge the amount of liquid which is to pass through close the valve covering the by-pass opening. in the preferred embodiment is the main dis- Since the valve actuator is operated by impact, 5 charge throat of the Pump. This may be a main its operation depends mainly upon the velocity tangential or volute or any other type of throat. of liquid in the discharge throa Since theA ve- The liquid which can pass through this channel locity of discharge is not a measure of the quanis determined by design to be the nquid which tity of liquid utilized as a priming vehicle, the is optimum for maximum rate of air removal in scheme does not give a satisfactory control. Im- 1o the particular pump. Any excess of liquid or of course, dependent upon mass, which is mixture of air and liquid within the pump bea function of volume and density, and upon the vvyond the stream which fills the metering chanaquare of thevelocity. Since the velocity is the nel is diverted to an overflow channel. overpowering factor and since it is not related' overflow channel may be in the preferred emto volume, the control is imperfect. At the very 1;, bodiinent and is the separate auxiliary discharge outset of operation the by-pass valve may be passageway of the hydraulic balance type of wide open, and could thus, theoretically, admit pump. These two channels need not be physa sui'iicient amount of liquid to the suction. ically separated, but'their functions are to be However, immediately uponstarting, assuming made distinguishable by the responsive means. the original quantity of liquid returned is ade- The direction of liquid ilow occurring in this large that choking of the return flow immediately the adequacy of liquid circulation in the pump results almost from the initiation of operation. itself. I provide a ilow control orifice or re- From then on, as suction increases, the control striction in the by-pass and I put the control is highly unsatisfactory. This scheme, therefore, of the effective opening of the flow control oriilce does not meet requirements. or restriction under means which is sensitive to A variation of the above scheme involves the' ow in the overflow channel. Thus, by coninsertion of the control element of the valve in trolling the size of the flow controlling orifice or the pump suction passageway. This avoids to a restriction in accordance with the amount and considerable extent the 'difilculty produced by 30 direction of ow in the overow channel, it is variable velocity, but introduces another difilv possible to circulate substantially the exact culty. The only medium capable of vactuating amount of fluid through the metering channel this valve is incoming liquid after the prime has which corresponds to maximum air handling. been completed. Consequently, there is no con- In referring to the metering channel and to trol whatsoever of the by-pass until water from 35 the overflow channel I do not intend to imply the outside source actually enters the pump. As that these channels must necessarily be sepaa result, if the by-pass opening is made large rate and independent. The concept involved is enough to meet the starting requirements it very that a certain size stream shall flow through quickly drowns the pump as the vacuum inthe pump and into the separator without efcreases. Hence, although a high air capacity 40 fecting any substantial control of the flow conmay result at extremely low vacuums, the hightrol orice, but when the stream is greater than er vacuums cannot be obtained except by rea certain size the excess shall exert an inuence stricting or limiting the size of the by-pass. Conupon closing oil the flow control orifice or resequently this scheme has practically the same striction so that the opening of the flow conshortcomings as an uncontrolled lby-pass in so trolled orifice is reduced to the point where the far as'the speed of priming is concerned. It has desired size' of flow is established. By using a the advantage of shutting of! all recirculation slot or throat for the discharge of the impeller after liquid inflow is established, but it does not to the separatorwhich slot or throat is relatively meet the requirements for high air capacity and long compared to its width, or is otherwise simihigh vacuum combined. 5U larly shaped, the two channels may find place in A third scheme uses a by-pass from the disspaced apart parts of the slot or throat. The charge back to the suction, which by-pass is flow which will fill a predetermined anterior part controlled by a valve operated by pressure in the of this slot or throat may constitute the perdischarge. This pressure valve remains open at mitted size of stream and being substantially inall times until pressure is built up in the sepeffective with respect to the vane or other conarator. Thereupon the pressure valve closes and trol element that effects or governs closure of shuts oil the by-pass. This has the same dethe flow control orice. When the outflow infects as the scheme using the control valve in the creases to the point of filling the other end of suction, but with the added diilculty that presthe slot or throat corresponding to a separate sure must be built up following actual entry of e0 overflow channel, the vane or other means for water into the pump. controlling the size of opening of the flow con- The problem which confronted ine, and which trolling orifice is actuated to reduce the size of the present invention solved, is the provision said return ow controlling oriilce. of a pump of the self-priming type which will When liquid from the outside source begins to provide a control the same as or equal to that 85 enter the pump it makes up a part of the fluid available by the hydraulic balance prlntiple while now through the main metering channel, and the the vacuums are appreciable, but which will also excess which thereupon shows up at the overflow have the added advantage of quick and ample channel acts upon the control orifice to reduce return of priming liquid when only gravity or a the amount' of liquid returned. Thereby any inlow difference of pressure is available. flow from the outside displaces so much of the I have found by experiment that for a large return circulation. When suillcient inflow occurs return of priming water from the separator to to flll the metering channel and begins to spill the impeller chamber a relatively large opening over into the overflow channel the bypass is 1511668559151- The mOSt feasible Place t0 diSPOSe partly or completely cut off by closing partly or this opening is between the separator and the completely the flow control orifice or restriction.

iiquid, and the impact of discharge operates to this by-pass, I provide a metering channel which quate, the velocity in the throat alsois sufficiently overflow channel is a gauge or determination of u Y may be connected to its passageway Thisl method of operation provides an ample supply of priming water at low `suctions and permits a principle of flow control similar tothe 'principle of hydraulic balance to control the operation at the higher suctions. so that substan` tially optimum conditions for maximum air handling capacity prevail throughout the entire range of suctions in this pump.

The above described method and principle of operation maybe embodied in a vertical form of pump as well as in a horizontal pump and the method and principle may be embodied in a pump with a single paix.` of main and overow channels, ory a pluralityof the same. Also this principle of iiow control may be combined with the hydraulic balance structure.

Now in order to -acquaint those skilled in the art with the manner of constructing and operating my invention I shall describe, ln conjunction with the accompanying drawing which forms a part of this specication, a speciiic embodiment of the invention.

In the drawing: 'I

Figure 1 is a vertical diagrammatic cross section 'of a pump embodying my invention; and

Figure 2 is a plan view of the same, showing a section through the separator on the line 2-2 of Figure l.

The pump herein illustrated comprises an intake trap member I, the pumping chamber 2 and a separator 3. The with a suitable clamping fIange 4 by which it a suitable suction pipe leading to a source of liquid at a lower level. Alternatively, it may lead to any othersource of fluid which it is necessary to extract by suction. The trap member I and the Pumping member 2 are joined by mating ilanges and 6, respectively. The separator 3, which i'n this case is showny as lying directly above the pumping chamber 2, is coupled to the pumping chamber by mating anges I and 8 and the separator 3 has a top outlet 8 surrounded by a clamping flange I0 by which it may be connected to a suitable discharge pipe. The trap member I includes the trap space II and this communicates through a relatively short neck member I4 with the eye of the impeller chamber I2. The separator member 3 has separating space I3 in whichv gas is permitted to separate from liquid during the operation of the pump, particularly during priming. The intake neck I4, pumping casing 2, is connected through a passageway -I5 to the bottom part of the separator space I3. The pumping chamber I2, in the specific form illustrated herein, is a concentric chamber, that is, it has a circularwall about the periphery of the impeller I6 which is swept by the impeller blades. The blades operate in a peripheral channel, which peripheral channel communicates with the main throat Il and its expanding passageway I l. The throat I'I and passageway Il' constitute in this structure the metering channel. The pumping channel communicates also with an auxiliary throat I8 andl its expanding passageway I8', the discharge of both passageways leading to the bottom of the separator space I3. The auxiliary throat I8 and I8' constitute in this structure the overflow channel. A swinging valve member I9, pivoted `at an intermediate point on a horizontal 'pivot 20, has a valve and'vane member 22 overlying and normally closing oft the upper end `of the expanding passageway I8' of the throat I8.

principle in the same,

intake trap- I is provided,

which leads to thev through the port 24 'I'he opposite extremity of the member I8 is an arcuate gate valve 23 which obstructs a concentric port 24. 'I'he gate valve member 23 is connected to the main body part of the valve member I8 by the arms 28 which aiIord a minimum obstruction to flow to liquid from the bottom of the chamber I3 down into the cavity 2l and into the intake of the pumping chamber. as a gate valve in order to be as little influenced by ilow through the port 24 as possible. It should in eilect be balanced so that neither -ow nor suction materially ailect its positioning. In other words, it is to take' a neutral position as controlled by the vane and valve member 22v at` the opposite end. The vane and valve member 22 is suitably counterbalanced byy sumcient weight of metal, or it may be overbalanced by a spring, so that its normal position is such as to close the outlet of/ the passageway I8'. This vane and valve member22 is partially housed or shrouded by a. vane or wall 28 which forms also apart of the supporting means for the hinge or pivot of the swinging member I8. The member 28 has laterally disposed arms 28, 23 which terminate in clamping llugs 3I by which the member 28 is bolted to the horizontal wall 82, and downwardly extending hinge lugs 33 supporting a hinge lpin 'for the pivot 20 of the member I9. a l

The impeller shaft 34 is adapted to be operated at substantially a predetermined speed for which the pump is'designed.

.The size of the port 24 and the passageway I5 for the return of priming water from the separator back into the intake of the pump is, by design, large enough to admit adequate volume of water at the head which will, in practice, prevail in the pump when it is ready to start. The throat I1 and its expanding passageway I1 are designed tobe of a size which will' right amount of -water to be carried in the vimpeller to produce maximum rate of air 'entrain-` ment and evacuation from the intake side. This is independent of speed and pressure.v The throat I'I and its passageway I l' thereby constitute a metermg channel for determining the proper cross section of flow of discharge fluid for optimum rate of air removal. 'Ihe auxiliary throat I8 and its passageway I 8 constitute the overiiow channel, ilow through which isdetected and responded to by the vane 22. This overflow channel has an additional functionin that it is designed to constitute a secondary discharge for liquid when the pump is primed and is operating upon liquid. It forms a parallel path for discharge and thereby increases the capacity of the pump to handle liquid. Its size may be designed accordingly. i' n 'I'he trap II in a pump embodying this invention need not be as large as on conventional pumps of the hydraulic balance type for the reason that the large bypass I5 will allow air from the discharge, that is, through the trap II, to

pass down through this bypass I5 and fill thel suction pipe upon the descent of the'column jofl liquid which drops when the pump stops its ac;

tion. The vacuum is thus broken without ref,4 quiring the liquid Yto be pulled out of theimpeller casing.

'I'he impeller I6 may be of any suitablefform-:' I prefer to utilize, in the concentric type arcas-'life The valve 23 is constructed merely one lspe- Wherea volute .opening 24.

is employed curved blades are preferable. The separator may be directly above the pump or may extend to one side, and, in fact, any suitable arrangement of the parts which secures the novel method of operation may be utilized.

The operation of the pump is as follows: Assuming that the pump has been connected to suction and discharge and a` suitable source of liquid provided for the suction, and that the pump body is charged with a charge of.priming water which may stand at a suitable level at or a short distance below the bottom of the intake opening 35, the shaft, 36 of the impeller I8 is rotated. The valve member I9 stands in substantially the position shown in full lines in Figures l and 2 when the shaft 34 starts'rotating. Immediately upon initiation of rotation, all the liquid which the impeller can reach will be driven up into the separator space I3 through both type of casing .throats I1 and I8, temporarily swinging the member I8 in counterclockwise direction to close off the port 28 by means of the gate valve 23. As soon however, as the volume of liquid in the impeller chamber I2 has been reduced to that whichiwill iill only the throat I1 and not discharge .through the throat I8, the valve I9 will rotate into clockwise position where the memberl 22 closes olf the top of the passageway I8', preventing the return of liquid through the said passageway I8' but permitting full flow through the port 28 of the bypass I5 into the intake of the pump.

It is assumed that the pump starts without any suction, that is, atmospheric pressure prevails in the the connected passageway leading to the eye of the impeller., The initial transfer of liquid may very slightly change this pressure relation, but let it be asforce for closing the valve sumed that the only head of liquid causing re- 4o turn flow through the bypass I5 is the head of liquid in the chamber I3. This is a small head, but the throat I5 is large enough to permit adequate return of liquid for filling the throat I1. Air will be entrained at the desired maximum rate and will be carried out through the" passageway I1' into the separator space I3 and there the gas escapes upwardly and out of the opening 9, the liquid being retained, and naturally the denser or more gas-free liquid gravitates to the bottom of the chamber I3. Here it returns, and the circulation is thus maintained and air evacuated from the intake side. Evacuation of air from the intake side immediately produces a pressure difference, prevailing in the separator and sub-atmospheric prevailing in the intake, whereby the ow of liquid through the bypass I5 is now impelled by an additional force, namely, the pressure difference added to the gravity head. Hence, if the passageway I5 is large enough to permit adequate return iiow under the influence of the gravity head alone, it is now too large for optimum gas removal when the added force of pressuredifferjust sufficient excess of liquid over that desired in the throat I1 will flow into the throat I8 and keep adjusting the position of the member I8 to continual throttling of the port 24, which port must be throttled as the pressure difference increases because of the greater velocity of liquid through the port 24, even though it be restricted.

The adjustment of the weight of the member 22 as to loading, whether by counterweight or by additional spring pressure, or other means, controls the amount of excess which must be produced in order to generate the necessary 23. The movement of the member 22 may be controlled mainly by impact of fluid in the throat I8; or it may be controlled mainly by flow, particularly since the member 22 may be shrouded by the member 28. This member 28 thus performs the dual function of preventing interference of the flow from the throat I1 with the member 22, and also it may serve in conjunction with'the swinging vane 22 as a weir or flow restriction to graduate thel position of the member 22 for a predetermined flow volume through the throat I8. Thus the stream of mixture which is the optimum stream for maximum rate of air removal is maintained by comparing it with the capacity of the throat I1. If the stream is greater than that which will pass through the throat, I1 it will spill over into the throat I8 and thereby further restrict the port opening 24 to maintain substantially a constant cross sectional size of the stream of liquid. This size of the stream is independent of velocity of the stream and independent of the pressure difference between the pressure prevailing in the pocket or separator I3 and the pressure prevailing in the intake side ofthe pump.

If now, at the prevailing suction, a small amount of liquid should begin to enter the pump through the intake, it would constitute a part of the ow through the throat I1 and to that extent would displace some of the circulating liquid that is, atmospheric ence acts upon the return flow. Therefore, more 6 liquid will return than is desired, that is, more than will fill the throat I1, and some will be carried over into the throat I8. As soon as liquid is carried over into the throat I8 the impact of the same upon the vane and valve member 22 will cause the same to swing inla counterclockwise direction, bringingthe gate valve 23 down over the'port 24 and reducing the size of the port Thereby the flow through the byby acting through the 'swinging member I8 to close off the return port 24. If the inflow gradually increases, this inflow substitutes itself for the circulating medium through the port 24, maintaining air removal at. optimum conditions until liquid in suiilcient volume ows into the intake to produce a complete closure of the bypass I5, and at that stage the pump by design is capable of operating without the necessity of further recirculation or of removing air without recirculation and continues to discharge liquid through both throats I1 and I8 in parallel, driving the same through the separator and out the discharge opening 8. During normal pumping of liquid after the pump has primed itself the overflow throat I8 becomes an auxiliary discharge throat, increasing the pumping capacity of the pump. If at any time the liquid supply should fall and air should enter the pump, the pump will immediately proceed to the recirculation method above described.

As above explained, the block of metal 35 which produces complete separation of the two passageways I1 and I8' is not essential, and, in fact, if -the shape of the discharge opening is suitably designed so that the two functional channels are provided in a single passageway the separation may be omitted. Two separate passageways as shown are more positive and efficient and constitute the preferred form.

The vane member 22 need not completely close pass I5 is reduced to the desired degree where 75 position,

As I have above indicated; the specic details of construction and the mode of arrangement of the parts may be widely varied within my invention, as dened in the appended claims.

1. A recirculating gas entraining pump comprising a separator, an impeller and cooperating casing, means providing a main discharge me' tering channel open at all times' from the casing into the separator, means providing an overow channel out of the casing into the separator,

means providing a return ow controlling orice between the separator and the impeller casing, and means controlled by fluid ilow throughthe overiiow channel for reducing the size of the flow controlling orice.

2. In a self-priming pump of the air entraining liquid recirculating type, an impeller casing containing an impeller channel, and having a main discharge channel `for discharging a predetermined flowof fluid mixture,- an auxiliary channel intended to operate as a parallel disch'f'ge channel when the impeller chamber is .nel for the discharge'of a predetermined ow of uid mixture out of the impeller chamber into the separator, and an adjacent auxiliary discharge channel for receiving any fluid mixture in excess of said predetermined ow, and means sensitive to a predetermined flow pf iluid mixture through said auxiliary discharge channelfor diminishing the flow of returning liquid in said bypass.

4. In a device of the class described a pump body comprising an impeller casing having a central inlet connection, an impeller channel, a pair of adjacent tangential discharge passageways communicating with said channel, the anterior one in the direction of rotation of the impeller forming a main passageway andthe posterior one forming an auxiliary passageway, a

separator casing providing a separator chamber communicating with Ysaid passageways, an intake member providing an intake trap chamber communicating with the intake of the impeller casing, a bypass between the separator and the intake, avalve controlling said bypass, and a flow sensitive element subject to flow in said auxiliary passageway for controlling the position of said valve.

5. In a device of the class described, a pump body comprising an impeller casing having a concentric pumping channel, an impeller working in said channel, there being two substantially adjacent tangential discharge passages comprising a primary passage and a secondary passage, the primary passagevbeing adapted 4to be lled with the stream of liquid and entrained gas durl ing priming, said primary passage determining the volume of liquid circulation during priming, a separatorcommunicating with said passages, an intake including a trap leading' to the eye of the impeller, a bypass between the separator and the intake, a normally open valve controlling said bypass, and means responsive to :duid ow outV of said secondary passage controlling the closing of said valve.

6. A self-priming centrifugal pump having an impeller chamber, an impeller working in the f chamber, an inlet connection including an intake traileading to theA central part of the impeller chamber, a separator, a bypass from the sepa-'- rator to the intake, said bypass being of a size such as to permit a predetermined stream of liquid to ow by gravity headinto the impeller which iiow provides substantially the optimum volume of liquid inthe impeller chamber for producing substantially the maximum rate of air entrainment and discharge, a valve for reducing the eifective opening of the bypass as the suction produced in the impeller chamber increases the head upon the return now, throating between the peripheral part of the impeller chamber and the separator, said throating including a channel capable of conveying the said predetermined stream of liquidmixed with air and a channel for` conveying discharged .fluid in excess of said predetermined stream, and means controlled by ow in said second channel for governing the shifting of said valve toward closed position.

HARRY E. LA BOUR. 

